KR102021047B1 - Bearing Element with Hydrophile Layer and the Producing Method thereof - Google Patents

Abstract

The present invention relates to an artificial joint including a surface made of a polymer material, and more particularly, to a bearing element capable of reducing a coefficient of friction by having a hydrophilic layer similar to the joint structure of a human body on a polymer surface by heating, and a manufacturing method thereof. will be.

Description

Bearing element with hydrophile layer and the producing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing element comprising a surface made of a polymer material, and more particularly to a bearing element capable of reducing a coefficient of friction by forming a hydrophilic layer similar to the joint structure of a human body on a polymer surface by heating. It is about.

The joints of the human body have ciliary tissue on its surface, which retains hydrophilicity to store body fluid. Therefore, the body fluid is stored in the ciliated tissue, and functions as a lubricant to enable natural movement of the human joint.

The joints of the human body are one of the important organs that perform the functions of determining the overall shape and balance of the body and supporting the weight among various parts of the human body. As such, joints are frequently used and further exposed to frequent shocks, the aging progresses over time, or the function of the joints is weakened or lost due to various diseases or accidents. Since such joint damage is difficult to treat in a natural state, development of artificial joints that can replace damaged joints is steadily progressing. The quality of life is remarkably improved through the treatment of artificial joints. Knee, shoulder, hip, and ankle joints are typical artificial joints.

1 is a view showing a knee joint of the artificial joint, which is disclosed in Korean Patent Laid-Open No. 10-2009-0076346 (2009.07.13.). The knee joint includes a femur element 5 largely replacing the articular surface of the distal end of the femur, a tibia element 7 replacing the articular surface of the proximal end of the tibia, and a femur located between the femur element and the tibial element. Bearing element 1 having an articulation surface in contact with the articulation surface of the element. Here, the femur element is in contact with the bearing element and the joint movement, the joint surface of the bearing element has a surface of the polymer material. The surface of the polymer material wears out during the joint movement with the femoral element and generates wear particles during the wear process. These wear particles are ingested by macrophage around the joint, and macrophages secrete specific cytokine and prostaglandin along with the ingestion of wear particles through a signaling system called RANKL. Osteoclast is greatly activated around the joint under the influence of secreted cytokine, and the balance between osteoblast and osteoclast is broken and osteolysis occurs, resulting in destruction of osteocytes around the artificial joint. The problem is that the joints lose their function.

Such a problem arises from the fact that the polymer material constituting the surface of the bearing element is hydrophobic, and thus has significantly lower lubricity than the joints of the human body having hydrophilicity. Therefore, studies to give hydrophilicity to the surface of the polymer is steadily progressing, but due to the high cost, it is not easy to popularize. This high cost may act as a factor that increases the burden on the patient in the reality that the demand for artificial joints is rapidly increased due to aging.

In addition, although there are studies to impart hydrophilicity by irradiating ultraviolet rays in the current research, artificial joints have curved surfaces, and the distance to the curved surface where ultraviolet rays reach is different for each curved portion, and thus the growing layer There was a problem that the thickness of was not uniform over the curved surface. Furthermore, the method of using ultraviolet rays causes difficulties in handling because it causes diseases such as skin cancer due to external exposure of ultraviolet rays.

Accordingly, while providing artificial joints having a hydrophilic polymer surface for the popularization of artificial joints, there has been a demand for the development of artificial joints that can be manufactured inexpensively and safely with a significant reduction in the friction coefficient using hydrophilicity.

The present invention has been made to solve the problems of the prior art, it is an object of the present invention to provide a bearing element and a method of manufacturing the same to reduce the friction coefficient to minimize the generation of wear particles.

Another object of the present invention is to provide a bearing element and a method of manufacturing the same, which can lead to popularization of artificial joints by reducing the manufacturing cost while minimizing the reduction of friction coefficient and the occurrence of wear particles.

It is still another object of the present invention to provide a bearing element having a hydrophilic layer having a uniform thickness for each part of a curved artificial joint and a method of manufacturing the same.

Still another object of the present invention is to provide a bearing element and a method of manufacturing the same, which can be improved in workability by being free from various diseases caused by ultraviolet exposure by using the heating method.

According to one embodiment of the present invention, the bearing element of the present invention has a hydrophilic layer on the surface of the artificial joint including the polymer surface.

According to another embodiment of the present invention, in the bearing element of the present invention, the hydrophilic layer is formed by grafting a polymer material on the polymer surface.

According to another embodiment of the present invention, in the bearing element of the present invention, the polymer material is a zwitterionic polymer material.

According to another embodiment of the present invention, the bearing element of the present invention is formed by attaching the polymer material to the polymer surface by grafting a polymerizable monomer.

According to another embodiment of the present invention, in the bearing element of the present invention, the monomer consists of a methacryloyloxy alkyl group and a sulfopropyl-ammonium hydroxide group.

According to another embodiment of the present invention, in the bearing element of the present invention, one end of the methacryloyloxy alkyl group is bonded to the polymer surface and the sulfopropyl-ammonium hydroxide group is the methacryloyloxy alkyl. Connected to the group.

According to another embodiment of the present invention, in the bearing element of the present invention, the monomer is 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide.

According to another embodiment of the invention, the bearing element of the invention, the hydrophilic layer has a brush structure consisting of a plurality of strands.

       According to another embodiment of the present invention, in the bearing element of the present invention, the polymer surface is formed of crosslinked polyethylene.

According to another embodiment of the present invention, in the bearing element of the present invention, each strand constituting the brush structure does not cause connection or entanglement between the strands.

According to another embodiment of the present invention, in the bearing element of the present invention, the coefficient of friction of the hydrophilic layer is 0.02 or less.

According to another embodiment of the present invention, in the bearing element of the present invention, the coefficient of friction of the hydrophilic layer is from 0.0090 to 0.02.

According to another embodiment of the present invention, in the bearing element of the present invention, the wear amount of the hydrophilic layer is 0.5 mm ³ or less.

According to another embodiment of the present invention, the manufacturing method of the bearing element of the present invention, the thermal initiator is coated with a thermal initiator on the surface by immersing and drying the bearing element having a polymer surface in a solution containing a thermal initiator for a predetermined time A coating step and a hydrophilic layer forming step of growing a hydrophilic layer by immersing the bearing element in a hydrophilic solution and heating for a predetermined time.

According to still another embodiment of the present invention, in the method of manufacturing a bearing element of the present invention, the hydrophilic solution is ultrapure water in which a monomer composed of a methacryloyloxy alkyl group and a sulfopropyl-ammonium hydroxide group is dissolved.

According to another embodiment of the present invention, in the method for manufacturing a bearing element of the present invention, the polymer surface of the bearing element is formed of crosslinked polyethylene.

According to another embodiment of the present invention, the manufacturing method of the bearing element of the present invention, the hydrophilic layer forming step is a brush structure forming one end of the methacryloyloxy alkyl group is bonded to the polymer surface to form a brush structure Steps.

According to another embodiment of the present invention, in the method for manufacturing a bearing element of the present invention, in the brush structure forming step, the sulfopropyl-ammonium hydroxide group is connected to the methacryloyloxy alkyl group.

(m은 고분자를 구성하는 반복된 단위의 수)을 가진 제1그룹을 폴리머표면에 결합시키고 중합시켜 스트랜드를 성장시키는 단계와, According to another embodiment of the present invention, the bearing element manufacturing method of the present invention, the hydrophilic layer forming step is a predetermined time by immersing a bearing element having a polymer surface coated with a thermal initiator in an ultrapure water solution in which a monomer is dissolved at a certain concentration Structural formula by heating

(m is the number of repeated units constituting the polymer) bonding the first group to the polymer surface and polymerizing to grow the strands,

제2그룹을 결합시켜 메타아크릴로일옥시 알킬 그룹(methacryloyloxy alkyl group과 술포프로필-수산화암모늄 그룹(dimethyl-(3-sulfopropyl) ammonium hydroxide group)으로 이루어진 구조식

(R1,R2,x 및 y는 Carbon Chain, A₁은 탄소(C) 또는 산소(0)) 모노머를 완성하는 단계를 포함한다.The bearing element having the strands grown by combining the first group is immersed in a solution in which an organic sulfur compound is dissolved at a predetermined concentration, and heated for a predetermined time to provide a structural formula on one side of the first group.

Structural formula consisting of a methacryloyloxy alkyl group and a dimethyl- (3-sulfopropyl) ammonium hydroxide group by combining a second group

(R 1, R 2, x and y are Carbon Chain, A ₁ is Carbon (C) or Oxygen (0)).

 According to another embodiment of the present invention, in the bearing element manufacturing method of the present invention, the monomer in the step of growing the strand is dimethylaminoethyl methacrylate, the organic sulfur compound is propanesultone.

The present invention has the following effects.

 The present invention, by reducing the friction coefficient to minimize the occurrence of wear particles to prevent the osteolysis phenomenon can be obtained to extend the service life of the artificial joint.

The present invention can reduce the friction coefficient and minimize the occurrence of wear particles while lowering the manufacturing cost can achieve the effect that can lead to the popularization of artificial joints.

The present invention can provide a bearing element having a hydrophilic layer having a uniform thickness for each part of the artificial joint having a curved surface.

By using the heating method, the present invention is free from various diseases due to ultraviolet exposure, and the workability is remarkably improved.

1 is a schematic diagram of the knee joint of the artificial joint.
2 is a cross-sectional view of a bearing element with a hydrophilic layer in accordance with one embodiment of the present invention.
3 is an enlarged view of a portion A of FIG. 2.
4A-4D illustrate the process by which the hydrophilic layer of FIG. 3 is formed.
5 is an XPS surface elemental analysis graph of a specimen surface without a hydrophilic layer.
6 is an XPS surface elemental analysis graph of a specimen surface with a hydrophilic layer.
7 is an XPS surface elemental analysis graph of a specimen surface with a hydrophilic layer.
8 is a graph showing a change in the coefficient of friction according to the conditions.
9A is a 3-D image of a confocal laser microscope after measuring the coefficient of friction in a state in which a specimen without a hydrophilic layer is immersed in water.
9B is a 3-D image of a confocal laser microscope after measuring a coefficient of friction in a state in which a specimen having a hydrophilic layer immersed in water after immersion only in a solution in which dimethylaminoethyl methacrylate is dissolved without undergoing organic sulfur compound treatment is immersed in water.
9C is a 3-D image of a confocal laser microscope after measuring a coefficient of friction in a state in which a specimen having a hydrophilic layer grown in a hydrophilic solution in which 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer was dissolved in water was immersed. .
FIG. 9D is a photograph taken after measuring a coefficient of friction in a state in which a specimen having a hydrophilic layer formed by heating after being immersed first in a solution in which dimethylaminoethyl methacrylate is dissolved and then secondly immersed in a solution in which Propanesultone is dissolved, is heated. 3-D image of a confocal laser microscope.
10A is a 3-D image of a confocal laser microscope after measuring the coefficient of friction in a state in which a specimen without a hydrophilic layer is immersed in an analogous biological solution.
FIG. 10B shows a confocal laser microscope photographed after measuring a friction coefficient in a state in which a specimen having a hydrophilic layer immersed in a solution in which dimethylaminoethyl methacrylate is dissolved and then heated by immersion in a similar biological solution without undergoing organic sulfur compound treatment. -D image.
10C shows a confocal laser microscope photographed after measuring a friction coefficient of a specimen having a hydrophilic layer grown in a hydrophilic solution in which 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer was immersed in a similar biological solution. 3-D image.
FIG. 10D shows the coefficient of friction in a state in which a specimen having a hydrophilic layer formed by heating after first immersing in a solution containing Dimethylaminoethyl Methacrylate and then immersing in a solution containing Propanesultone in a second state and then heating. 3-D image of a confocal laser microscope taken.
11 is a graph showing a change in the amount of wear according to each process condition after measuring the friction coefficient.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention is to form a hydrophilic layer on the surface of the bearing element which is a part of the joint movement of the components of the artificial joint to replace the joint of the human body. Joints of the human body largely include the hip joint, knee joint, shoulder joint, ankle joint. Other than that, all the parts of the human body in which the bones and bones make relative movement are called joints, and the implants that replace them are called artificial joints. The element in which the hydrophilic layer is formed in the artificial joint means a bearing element having a whole surface made of polymer material or at least a joint surface having a polymer coated surface. Bearing elements are joint motions with other elements. If the femur and tibia elements perform the function of bearing elements, they may be bearing elements. The polymer material is preferably polyethylene (PE), and crosslinked polyethylene (CLPE) is particularly suitable.

As shown in FIG. 2, the bearing element 1 of the present invention comprises a substrate comprising a polymer material (hereinafter referred to as a 'polymer surface' 2) and a hydrophilic layer 4 bonded to the surface thereof. It includes.

The substrate may be formed entirely of a polymer material so that the surface 2 may be a polymer material. However, only the surface of the joint motion may be partially coated with the polymer material to form the polymer surface 2.

As shown in FIG. 3, the hydrophilic layer 4 has a brush structure comprising one or more strands 41. The brush structure is such that one end of each strand is bonded to the polymer surface 2 and the other end remains free. And, the neighboring strands 41 are maintained so as not to entangle with each other in the body fluid. Maintaining non-tangling in body fluids means that ions are present in the body fluid that can offset the tendency for intramolecular or intermolecular binding between the strands, and these ions wrap up the molecules that make up the strand, resulting in intermolecular or intramolecular binding of the strands. Reduce the tendency to prevent tangles.

4A to 4D show the process of growing the hydrophilic layer 4 on the polymer surface 2. First, a method of manufacturing a bearing element having a hydrophilic layer will be described.

The bearing element manufacturing method consists of a thermal initiator coating step and a hydrophilic layer forming step.

, Dicumyl peroxide :

, Lauroyl peroxide : The thermal initiator coating step is a step of coating a thermal initiator on the polymer surface by immersing the bearing element having a polymer surface in a solution containing the thermal initiator for a predetermined time and drying. The thermal initiator may be used benzoyl peroxide. The bearing element is dipped in a solution containing a thermal initiator for a certain time and then dried. Acetone may be used as the solvent for dissolving the thermal initiator. As a thermal initiator 2,2'-Azobisisobutyronitrile (AIBN):

, Dicumyl peroxide:

, Lauroyl peroxide:

, Potassium persulfate :

이 사용될 수 있다.

, Potassium persulfate:

This can be used.

In the hydrophilic layer forming step, the dried bearing element is again immersed in the hydrophilic solution in which the monomer is dissolved, and then heated for a predetermined time to form the hydrophilic layer 4 on the polymer surface 2. The monomer is a hydrophilic monomer having zwitter-ion in a solution, and is composed of a methacryloyloxy alkyl group and a sulfopropyl-ammonium hydroxide group. The monomer has the following structural formula.

Structural Formula of Zwitterionic Monomer

R ₁ , R ₂ includes all C _n H _2n-1 (n = 1,2,3 ,,,, 6) as carbon chain, x, y also includes all zero or more as carbon chain, A ₁ means C (carbon) or O (oxygen).

Preferably, the monomer having easy zwitterion and low cost zwitterion is suitable for 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide having the following structural formula.

[Structure of 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide]

The hydrophilic layer forming step includes a brush structure forming step.

Hereinafter, the brush structure forming step will be described.

The hydrophilic solution may be an ultrapure water solution in which the monomer is dissolved in distilled water and impurities are removed. The distilled water is ultra-pure grade water as a third distilled water to adjust the pH, and firstly remove the organic and inorganic materials, and then make a second purified water through reverse osmosis membrane, sterilization and the like.

When the dried bearing element 1 is immersed in the hydrophilic solution in which the monomer is dissolved for a predetermined time, as shown in FIG. 4A, radicals are generated on the polymer surface coated with the thermal initiator and the polymer surface is dried. It is surrounded by a zwitterionic monomer 410 in the silver solution, and as shown in FIG. 4B, the methacryloyloxy alkyl group 412 of the monomer has one end of the bearing element. The radicals on the polymer surface 2 are grafted to the sites where the radicals are generated, and the other end remains free. In this case, the sulfopropyl-ammonium hydroxide group (dimethyl- (3-sulfopropyl) ammonium hydroxide group, 414) is bonded to the polymer surface (2) in the state bonded to the methacryloyloxy alkyl group (methacryloyloxy alkyl group, 412) Will remain unbound. Subsequently, as shown in FIG. 4C, one strand of polymer is polymerized while the other monomer 410 is polymerized at the free end of the methacryloyloxy alkyl group 412 already bonded to the polymer surface 1. It grows to (41). Through this process repeatedly, as shown in FIG. 4D, a plurality of strands 41 grow on the polymer surface to form a hydrophilic layer 4 having a brush structure.

The hydrophilic layer 4 consists of a plurality of strands, the strands comprising a zwitterionic sulfopropyl-ammonium hydroxide group, which may be considered to cause entanglement between strands, but as previously seen, The 41 are kept intact in the body fluids. Maintaining non-tangling in body fluids means that ions are present in the body fluid that can offset the tendency for intramolecular or intermolecular binding between the strands, and these ions wrap up the molecules that make up the strand, resulting in intermolecular or intramolecular binding of the strands. Reduce the tendency to prevent tangles. The hydrophilic layer is different from the ciliated layer formed on the joint surface of the human body and its components, but the structure is similar, so that the friction coefficient and the amount of wear can be significantly reduced by providing a lubricating function by supporting the body fluid. By using a low cost monomer, the above effects can be obtained.

According to another embodiment of the present invention, the brush structure forming step includes a first step and a second step.

In the first step, a bearing element having a polymer surface coated with a thermal initiator is immersed in an ultrapure water solution in which a monomer is dissolved at a predetermined concentration, and then heated for a predetermined time to bond the first group having the following structural formula to the polymer surface and polymerize the strand. Step of growing.

[Structure Formula of First Group]

In the structural formula of the first group, m refers to the number of repeated units constituting the polymer.

 Here, the monomer is a monomer having a first group having the above structural formula, preferably Dimethylaminoethyl Methacrylate, most preferably 2- (Dimethylamino) ethyl Methacrylate (DMAEMA).

In the second step, the bearing element having the strands grown by combining the first group is immersed in a solution in which an organosulfur compound is dissolved at a constant concentration and heated for a predetermined time to form a second group on one side of the first group. By combining to complete the polymer consisting of the aforementioned methacryloyloxy alkyl group (412) and sulfopropyl- ammonium hydroxide group (dimethyl- (3-sulfopropyl) ammonium hydroxide group, 414) of the first embodiment Will form a hydrophilic layer. The organosulfur compound is preferably Propanesultone, more preferably 1,3-Propanesultone.

Structural formula of the second group

Final monomer structural formula

The above embodiment is distinguished from the first embodiment in which the hydrophilic layer is formed through one coating process in that the coating process is performed in two steps.

Hereinafter, the effect of the embodiment of the present invention through various experiments.

[Preparation of Psalms]

Preparation of Comparative Example 1 and Example 1

A specimen prepared without any treatment on a disk (diameter 20 mm × thickness 5 mm) made of crosslinked polyethylene (CLPE, Orthoplastice, USA) was prepared as Comparative Example 1.

A disc made of cross-linked polyethylene (CLPE, Orthoplastice, USA) (diameter 20 mm x thickness 5 mm) was immersed in acetone (Sigma-aldrich, USA) solution in which benzoyl peroxide (Sigma-aldrich, USA) was dissolved at a concentration of 55 mM. After drying. Through this process, acetone is evaporated and the disk surface remains coated with benzoyl peroxide.

Subsequently, heat the plate at 80 ° C. on a hot plate (Korean Science, Korea) for 24 hours while immersing a dry disk in ultrapure water solution in which monomer 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide was dissolved at the following concentration. Was added to coat. The coated specimen was washed with ultrapure water and ethanol and dried at room temperature to prepare Example 1.

Example 2

A disk (diameter 20 mm x thickness 5 mm) made of crosslinked polyethylene (CLPE, Orthoplastice, USA) was placed in acetone in which benzoyl peroxide was dissolved at 55 mM concentration for 30 seconds and then dried. A dry disk was placed in ultrapure water in which DMAEMA was dissolved at a concentration of 0.5 mol / L, and coated by heating at 80 ° C. for 24 hours on a hot plate. Then, DMAEMA-coated discs were placed in toluene (Sigma-aldrich, USA) in which 1,3-Propanesultone (PS; Sigma-aldrich, USA) was dissolved at a concentration of 3 mol / L, and then heated to 50 ° C. on a hot plate (Korean Science, Korea). The coating was applied by heating for 24 hours. The coated specimen was washed with toluene and ethanol and dried at room temperature to prepare Example 2.

Comparative Example 2

A disk (diameter 20 mm x thickness 5 mm) made of crosslinked polyethylene (CLPE, Orthoplastice, USA) was placed in acetone in which benzoyl peroxide was dissolved at 55 mM concentration for 30 seconds and then dried. Dried CLPE was added to ultrapure water in which Dimethylaminoethyl Methacrylate (DMAEMA; Sigma-aldrich, USA) was dissolved at a concentration of 0.5 mol / L, and coated by heating at 80 ° C. for 24 hours on a hot plate. The coated specimen was washed with ultrapure water and ethanol and dried at room temperature. Through this process, Comparative Example 2 was prepared in which the first group was coated on the disk surface.

Comparative Example 3

The disk was placed in acetone in which benzophenone (Sigma-aldrich, USA) was dissolved at a concentration of 10 mg / ml and dried for 30 seconds. UV irradiation of 40 mW / ㎠ using a UV irradiator (litzen, Korea) in a dry disc of ultrapure water dissolved in monomer 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxid at a concentration of 0.5 mol / L The hydrophilic layer was coated by irradiation for 90 minutes in strength. The coated specimen was washed with ultrapure water and ethanol and dried at room temperature.

[Experiment 1]: XPS surface elemental analysis

In order to confirm that the hydrophilic layer of the zwitterionic polymer was well coated on the surface of the polymer, elemental analysis of the surface was performed for Comparative Examples 1 and 1 and 2 using an X-ray photoelectron spectroscopy (XPS: FEI, USA). Was implemented.

Comparative Example 1 shows only peaks corresponding to C _1s as shown in FIG. 5, while Examples 1 and 2 correspond to C _1S , N _1S and S _2P as shown in FIGS. 6 and 7. Peaks were observed respectively. Thus, it can be seen that the 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer was stably bound to the polymer surface.

[Experiment 2] Friction Coefficient

In order to confirm the change of the friction coefficient of the hydrophilic layer, for the Comparative Examples 1, 2, 3, Examples 1 and 2, using a friction wear tester (CETR, USA), a load of 0.98N and 2mm / s 100 mm sliding experiments were carried out at a speed of 100 times.

As shown in Table 1 and FIG. 8 below, compared to Comparative Examples 1 to 3, Examples 1 and 2 showed a low coefficient of friction. Compared to Comparative Example 2 having a hydrophilic layer coated only with dimethylaminoethyl methacrylate and Comparative Example 3 having a hydrophilic layer coated by irradiating UV with a 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer solution, Example 1 was formed by using a 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer solution and the first coating using Dimethylaminoethyl Methacrylate monomer solution and then using 1,3-Propanesultone solution Secondly coated Example 2 has a lower coefficient of friction. In addition, when comparing Examples 1 and 2, it was also confirmed that Example 2 has a lower coefficient of friction than Example 1. Thus, 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide It was confirmed that the method of forming the hydrophilic layer by dividing in two times is advantageous in forming the hydrophilic layer having a lower coefficient of friction than the method of forming the hydrophilic layer at once using the monomer solution.

Change in friction coefficient Item Coefficient of friction water Analogous biological solution Comparative Example 1 0.0284 0.0222 Comparative Example 2 0.0227 0.0198 Comparative Example 3 0.0093 0.0107 Example 1 0.0207 0.0155 Example 2 0.0102 0.0090

[Experiment 4] Abrasion Measurement

To determine the amount of abrasion reduction of the specimens subjected to the friction test after the friction coefficient was measured in the water (and similar SBF), a confocal microscopy (Lecia, Germany) was used. Through the measurement, the surface damage and wear of the specimens of Comparative Examples 1 and 2 and Examples 1 and 2 were measured.

Surface damage

9A and 10A are 3-D images of Comparative Example 1 in water and similar biological solutions, respectively. FIGS. 9B and 10B are 3-D images of Comparative Example 2 in water and analogous biological solutions, respectively. 9C and 10C are 3-D images of Example 1 in water and similar biological solutions, respectively, and FIGS. 9D and 10D are 3-D images of Example 2 in water and analogous biological solutions, respectively. to be. Looking at these drawings, it can be seen that the damage degree is gradually lowered in the order of Comparative Example 1, Comparative Example 2, Example 1, Example 2.

Wear

Looking at the change in the degree of wear according to the process conditions with reference to [Table 2] and Figure 11 below, compared to Comparative Examples 1 and 2, the amount of wear of Examples 1 and 2 is lower, Example 2 is less wear than Example 1 Confirmed. Therefore, the method of forming a hydrophilic layer by dividing it twice in a method using a 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide monomer solution is less than a method of forming a hydrophilic layer by a hydrophilic layer having a lower coefficient of friction It was found to be advantageous for forming

Change in wear Item
Wear water  Analogous biological solution Comparative Example 1 1.34 1.03 Comparative Example 2 0.85 0.80 Comparative Example 3 0.43 0.44 Example 1 0.79 0.65 Example 2 0.44 0.42

Claims (19)

A polymer surface, and a hydrophilic layer formed on the polymer surface by a thermal polymerization method,
The hydrophilic layer is formed by grafting a polymer material on the polymer surface,
The polymer material is a zwitterionic polymer material, and is formed by attaching a polymerizable monomer to the polymer surface by graft polymerization,
The monomer comprises a methacryloyloxy alkyl group and a sulfopropyl-ammonium hydroxide group,
One end of the sulfopropyl-ammonium hydroxide group is bonded to the methacryloyloxy alkyl group, the other end of the sulfopropyl-ammonium hydroxide group forms a free end,
One end of the methacryloyloxy alkyl group of one monomer is bonded to the polymer surface, the other end of the methacryloyloxy alkyl group of one monomer forms a free end, and the methacryloyloxy alkyl group of the one monomer Characterized in that one end of the methacryloyloxy alkyl group of the other monomer is bonded to the free end of the growth to the strand. delete delete delete delete delete The bearing element of claim 1, wherein the monomer is 2- (methacryloyloxy) ethyl dimethyl- (3-sulfopropyl) ammonium hydroxide. The bearing element according to claim 1 or 7, wherein the hydrophilic layer has a brush structure composed of a plurality of strands. The bearing element of claim 8, wherein the polymer surface is crosslinked polyethylene. 10. The bearing element according to claim 9, wherein each strand constituting the brush structure is free of connection or entanglement between strands. The bearing element of claim 10, wherein the coefficient of friction of the hydrophilic layer is 0.0090 to 0.02. The bearing element of claim 10, wherein the amount of wear of the hydrophilic layer is 0.5 mm ³ or less. A thermal initiator coating step of coating the thermal initiator on the surface by immersing and drying a bearing element having a polymer surface in a solution containing the thermal initiator for a predetermined time;
And immersing the bearing element in a hydrophilic solution, followed by heating for a predetermined time to grow a hydrophilic layer,
The hydrophilic solution is ultrapure water in which a monomer composed of a methacryloyloxy alkyl group and a sulfopropyl-ammonium hydroxide group is dissolved,
One end of the sulfopropyl-ammonium hydroxide group is bonded to the methacryloyloxy alkyl group, the other end of the sulfopropyl-ammonium hydroxide group forms a free end, and one end of the methacryloyloxy alkyl group of one monomer It is bonded to the polymer surface, the other end of the methacryloyloxy alkyl group of one monomer forms a free end, and the methacryloyloxy of the other monomer at the free end of the methacryloyloxy alkyl group of the one monomer. Characterized in that one end of the alkyl group is bonded to grow into strands, bearing element manufacturing method. delete The method of claim 13, wherein the polymer surface is crosslinked polyethylene. 16. The method of claim 15, wherein the forming of the hydrophilic layer comprises a brush structure forming step in which one end of the methacryloyloxy alkyl group is bonded to the polymer surface to form a brush structure. delete The method of claim 13, wherein the forming of the hydrophilic layer is performed by immersing a bearing element having a polymer surface coated with a thermal initiator in an ultrapure water solution in which a monomer is dissolved at a predetermined concentration. Structural formula by heating

(m is the number of repeated units constituting the polymer) bonding the first group to the polymer surface and polymerizing to grow the strands,
The bearing element having the strands grown by combining the first group is immersed in a solution in which an organic sulfur compound is dissolved at a predetermined concentration, and heated for a predetermined time to provide a structural formula on one side of the first group.

Structural formula consisting of a methacryloyloxy alkyl group and a dimethyl- (3-sulfopropyl) ammonium hydroxide group by combining a second group

(R1, R2, x and y is Carbon Chain, A ₁ is carbon (C) or oxygen (0)) A method of manufacturing a bearing element comprising the step of completing the polymer. 19. The method of claim 18, wherein the monomer in growing the strand is dimethylaminoethyl methacrylate and the organosulfur compound is propanesultone.

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